An amplifier only amplifies. It needs a generator to generate the signal to be amplified.
In the other hand, a PC with Spooky2 doesn't generate any freq. It only sends instructions to the generator (via USB), for the freqs to be generated .
So you can't get any useful freqs from the rig you're proposing.
You could use a PC with a sound generation software installed on it, to feed data to an amplifier, and get freqs, but sound amplifiers work in the 20-20,000 Hz range only.
You could even use an MP3 player to feed the freqs to the amplifier (in the audible range only).
For more details, please check the link: